Clutch not disengaging but pedal returns fine
 

Hey folks,

I've been STFA for quite a while now, and most of the posts I see concerning probelms with the hyd clutch system on these cars starts with a pedal that won't return. This makes sense to me, but my current situation does not exactly.

Let me start by saying I just bought this basketcase of a 1990 CQ with 220K miles. The engine runs pretty well, but the rest of the car is a bit of a mess. Typical not-very-well-maintained 20 year old Audi. But hey, it was cheap (so far)! My daily driver is a 2001 A6 2.7T, and my wife's is a 2004 Touareg V8. I have had countless watercooled VWs, and my first Audi was an urS4 a couple years ago.

I found the CQ in a barn, it had been sitting for about 3 years following a moderate left front corner crash. Nothing major. I connected a new battery, got it started, and drove it onto the trailer and off the trailer to where it has sat in my driveway for about 3 weeks. The clutch worked fine when I picked it up, but now will not disengage at all. I can get the tranny in gear with the engine off, but not while it's running. The pedal seems to have a normal amount of resistance, but no amount of pumping changes the situation. The clutch just won't release!

I have ordered a new slave (not here yet), and by the looks of most of the archived threads, you guys recommend doing the master at the same time.

I just find it odd that the pedal returns, has a seemingly normal amount of resistance, but won't release at all. I find it especially odd that it decided to fail just sitting there, after it seemed to work fine before. Maybe all that time sitting built up some corrosion in the cyls., and the seal got chewed up during the few times I operated the clutch to get the car on and off the trailer.

Any of you experienced guys have any other suggestions besides just replacing both cyls.? I can't imagine enough air getting into the system that bleeding would actually help, but not sure...

Thanks!

Re: Clutch not disengaging but pedal returns fine ...
 

[Hi Sir.

I have heard this "replace both cylinders" repair method before and I'm not sure if this is entirely necessary or true. Is it perhaps due to an insufficient diagnosis having been made.

The explanation that I got for "do both" was that the root cause of the failure does in both cylinders in short order and this saves a return trip to replace the other one. Not entirely a satisfactory explanation as far as I'm concerned. I think it precludes simply <i>guessing</i> which is the culprit.

The Clutch M/C takes fluid from the Reservoir on top of the Brake M/C at a particular height. Is your Res. fluid level above this hose's attachment point? If no, your Clutch M/C may be starved of fluid.

My clutch release function weakens in extreme hot weather which I take to mean water dilution of the fluid due to it's age. Is your clutch slave cylinder fluid perhaps now frozen? Would warming/bleeding it help?

Hope this helps. Please post your fix.

Hi
I actually have the same problem with my 2000 a4 2.8 quattro, did you get yours fixed??
I just replaced the new clutch, fork release bearing and pressure plate (LUK) kit. i drove the car for about 4 miles and sudenly clutch wouldnt disengage...the clutch pedal was up and holding enough pressure but when depressed it wouldnt disengage!
I also checked the slave there is no licks and the Master looks fine, bone dry!
please help if you know more from this...
Thanks!